BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
FIG. 1 is a section view of an initiator that includes an initiating component having an end configured to mate with a corresponding end of a flammable component.
FIG. 2 is a section view of an initiator according to an alternative embodiment that includes an initiating component having an end movably coupled to a mating end of a flammable component.
FIG. 3 is a partial section view of an initiator according to aspects of the invention assembled within a radial cutting torch that is disposed in a tubular to be cut.
FIG. 4 is a partial section view of an initiator according to aspects of the invention assembled within a perforating gun that is disposed in a casing to be perforated.
DETAILED DESCRIPTION
Embodiments of the invention generally relate to initiators that have a two component design and utilize a flammable solid and an exploding bridge wire (EBW), an exploding foil initiator (EFI) or any other suitable bridge wire mechanism. While applications are illustrated for use in downhole tools, the initiators disclosed herein enable detonation of various explosives or ignition of different flammable materials in any other application requiring such initiation. Since the two components of the initiator are individually non-explosive, the initiators described below can be shipped, handled and stored as a non-explosive kit prior to final assembly of the two components without special requirements associated with explosives. For some embodiments, the components of the initiators may be shipped in separate containers to a location where they are finally assembled for use. Furthermore, the initiators once finally assembled continue to provide safety benefits associated with initiators utilizing the EBW and the EFI, such as being radio safe, and can be disassembled if necessary.
FIG. 1 shows an initiator 100 that includes an initiating component 102 having an end 101 configured to mate with a corresponding end 103 of a flammable component 104. The initiating component 102 includes a housing 106 that supports an initiating device 108 proximate the end 101 of the initiating component 102. Preferably, an EBW forms the initiating device 108. For other embodiments, an EFI forms the initiating device 108.
The flammable component 104 includes a sleeve 112 for holding a flammable substance 114. Preferably, the flammable substance 114 includes a flammable or detonating material such as thermite, lead azide, pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (cyclonite or RDX) or any other suitable energetic material. A barrier 116 such as a piece of paper or MYLAR® and an end cap portion 118 of the sleeve 112 may further contain the flammable substance within the sleeve 112.
Lead wires 110 connect to the initiating device 108 and exit the housing 106 for connection to appropriate electrical circuitry used to set off the initiating device 108 and hence activate the initiator 100. Accordingly, the lead wires 110 can exit the housing 106 as individual wires or as a coaxial for hookup or as a multi-pin assembly into which a cable mates for connection to the electrical circuitry. Commercially available electrical circuitry exists for selection depending on the type of the initiating device 108 and the specific application of the initiator 100. Only one of the lead wires 110 may be required for some embodiments such as when the initiator 100 is grounded.
Final assembly of the components 102, 104 of the initiator 100 does not occur until on location and at a desired time prior to when the initiator 100 is needed. The ends 101, 103 of the components 102, 104 facilitate coupling of the components 102, 104 to one another during final assembly of the initiator 100. Specifically, the ends 101, 103 define any type of mechanical interrelatedness used to form a connection, such as a threaded connection. Once finally assembled, the initiating device 108 aligns in close proximity to the flammable substance 114 such that the initiating device 108 can be caused to ignite the flammable substance 114 upon activating the initiator 100.
FIG. 2 illustrates an initiator 200 according to an alternative embodiment that includes an initiating component 202 having an end 201 movably coupled to a mating end 203 of a flammable component 204. Similar to the initiator 100 shown in FIG. 1, the initiator 200 includes a flammable substance 214 disposed in a sleeve 212 of the flammable component 204 and lead wires 210 connected to an initiating device 208 held within a housing 206 of the initiating component 202. The initiating component 202 is initially held in a disarmed position with the initiating device 208 spaced away from the flammable substance 214 such that the flammable substance 214 does not ignite to activate the initiator 200 even if the initiating device 208 is set off. Additionally, an optional filler material 220, such as a silicone oil or petroleum jelly, disposed within the sleeve 212 between the initiating device 208 and the flammable substance 214 further blocks the initiating device 208 from the flammable substance 214 while in the disarmed position.
Final assembly of the components 202, 204 places the initiator 200 in a ready position (see FIG. 4) only when on location and at a desired time prior to when the initiator 200 is needed. The final assembly involves sliding the components 202, 204 relative to one another to place the initiator 200 in the ready position such that the initiating device 208 can be caused to ignite the flammable substance 214 upon activating the initiator 200. The smaller outer diameter of the end 201 of the initiating component 202 enables relative sliding movement of the initiating component 202 within the larger inner diameter of the sleeve 212. A port 222 within the sleeve 212 permits ejection of the filler material 220 from within the sleeve 212 when the initiating component 202 moves from the disarmed position to the ready position. Any type of mechanical interrelatedness between the components 202, 204 can selectively retain the components in either the disarmed position prior to final assembly or the ready position after sliding the components 202, 204 to align and place the initiating device 208 in close proximity with the flammable substance 214. This sliding movement of the initiating component 202 relative to the flammable component 204 can occur at the surface by an operator or once the tool is downhole by an actuation mechanism.
FIG. 3 shows the initiator 100 after final assembly thereof and coupling with a radial cutting torch 300 disposed in a tubular 302 to be cut. An initiator sub 304 coupled to the radial cutting torch 300 houses the initiator 100 in close proximity with wafers of thermite 306 disposed in the radial cutting torch 300. The initiator 100 electrically connects to an electronics module 310 designed to activate the initiator 100 upon receipt of a signal through the wire line 308, which can also be used to lower the entire assembly into the wellbore. In operation, the flammable substance 114, such as thermite, in the initiator 100 ignites upon activating the initiator 100. Since the initiator 100 is capable of igniting the thermite 306 in the radial cutting torch 300 at distances in excess of five inches away, ignition of the flammable substance 114 in the initiator 100 then ignites the thermite 306 in the radial cutting torch 300. The ignited thermite 306 flows out a nozzle 312 of the radial cutting torch 300 to produce a high-velocity jet of molten metal and gas that cuts the tubular 302.
FIG. 4 shows the initiator 200 after final assembly thereof and coupling with a perforating gun 400 lowered by a wireline 408 to a desired location in a casing 402 to be perforated. An initiator sub 404 coupled to the perforating gun 400 houses the initiator 200 in close proximity with a detonating cord 414 that is optionally disposed within a booster 406. Generally, the booster 406 includes an aluminum shell filled with explosives and crimped to the detonating cord 414. However, any commercially available booster such as used between tool joints can provide additional thermal and shock sensitivity necessary to ensure that detonation of the detonating cord 414 occurs and goes to a high order explosive. The detonating cord 414 clamps to a back end of shaped charges 412 arranged throughout the perforating gun 400. In operation, an electronics module 410 supplies the required voltage and current to activate the initiator 200 at the desired time. Once ignited, the flammable substance 214, such as thermite, within the initiator 200 detonates the booster 406 and detonating cord 414. The detonation propagates along the detonating cord 414 to set off the shaped charges 412 that penetrate the casing 402.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Patent Application
20080047449
